As an SEO stand point in this day and age you should never use nofollow to attempt to shape Google the PR flow or to stop Google crawling those pages.
There is no robots.txt, meta or link attitude that stops Google from Crawling your pages, and theres many reasons for this. There is however ways of telling Google not to index and cache this pages.
It's also worth mentioning that Google does not obey by the nofollow when indexing and why the attribute sounds like it would - it doesn't. Nofollow will not stop Google crawling pages since many links on that page could be follow and in this day and age most outbound links on sites are nofollow. Nofollow should be used when you don't want to pass any of your rankings to their outbound site, and should never be used internally since it has been abused in recent years and Google has clamped down on sites that use it internally.
Google only flows juice between pages that actually make it into their index so with this you can actually tell Google what Pages you want to have the most Juice by not indexing those pages.
What you need to do is actually use a meta name on the page that you don't want juice flowing to and also you don't want Google indexing it.
<meta name="robots" content="noindex, follow">
It is also advisable to use robots.txt blocking the same pages from being indexed.. But the meta tag works better than robots, while having both is the best method.
Including that within the header of the pages that you do not want to index will tell the search engines not to index this page, HOWEVER! the follow command you notice will mean that if someone links to that page even though its not indexed it will flow the juice to the rest of the site meaning if someone links to your page that isn't indexed on Google or any other search engine for that matter your site will benefit.
